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J Renart

Publications and source records attributed to J Renart.

At least 19 recordsLinked to original sources
PubMed1994

Structure and expression of a polyubiquitin gene from the crustacean Artemia.

We have characterized two polyubiquitin genes from the crustacean Artemia franciscana. One of them, Ubi1, has nine ubiquitin units and an intron of a minimum size of 3.5 kb that ends 7 bp before the initiator ATG. The 5' end of the transcript from this gene has been identified by anchored PCR. The existence of the other gene (Ubi2) was inferred from several cDNA clones that differ from Ubi1 in the C-terminal extension and in the 3' untranslated region as well as in the nucleotide sequence of the coding region. We find two transcripts of ubiquitin genes, of 2.7 and 3.3 kb. Hybridization of RNA blots with an oligonucleotide specific for Ubi2 gene demonstrates that this gene codes for the 3.3 kb transcript. Ubiquitin messenger RNAs are present in the dormant embryos and their steady-state levels are maximum at 8 h after resumption of development, declining thereafter. The Ubi2 gene transcripts are less abundant but its proportion in relation to the other transcript does not vary with development.

Amino Acid Sequence↗
PubMed1992

Biochemical characterization of Artemia ras p21.

The biochemical properties of Artemia ras proteins (p21) have been studied after immunoprecipitation with the monoclonal antibody Y13-259. The ras products bind GTP and GDP, and have GTPase activity. Artemia p21 was unable to hydrolyze Gp4G, although this dinucleotide exhibits high affinity for the protein. Our results demonstrate that the protein(s) recognized by the Y13-259 antibody in this crustacean behave as typical mammalian ras p21s.

Animals↗
PubMed1989

The 5S rRNA-histone repeat in the crustacean Artemia: structure, polymorphism and variation of the 5S rRNA segment in different populations.

5S rRNA genes are linked to the histone genes in the 13 populations of the crustacean Artemia that we have studied. In all cases, two types of repeat units are found. Southern blot analysis of all populations shows that they can be grouped into three classes: a) American bisexuals; b) Eurasian bisexuals, and c) parthenogenetic organisms (all from Eurasia). Restriction analysis of a bisexual population from San Francisco Bay shows that the two repeat units are of 9.0 and 8.5 kb (with minor heterogeneities of restriction sites). In parthenogenetic organisms, the two repeat units are of approximately 12 kb. Sequencing data from the region of the 5S rRNA from the San Francisco Bay population, shows that in both types of units, the single 5S rRNA gene (315 bp in length), is located 430 bp downstream the 3' regulatory sequences of the H2A gene, the last gene in the histone cluster. We have isolated three clones that contain 5S rRNA sequences. Two of them (one from an American bisexual and the other from a parthenogenetic population) contain histone and 5S rRNA genes, both with the same transcriptional polarity. The third clone, lacking histone genes, is likely to be an orphon derived from the parthenogenetic population.

Amino Acid Sequence↗
PubMed1989

Differential expression of a gene highly homologous to c-ras during the development of the brine shrimp Artemia.

We report the identification of p21ras and a cDNA coding for it in the crustacean Artemia. The monoclonal antibody Y13-259 immunoprecipitates a polypeptide of 21.5 kDa in 24 hr-old larvae. The homology of p21ras with the Drosophila melanogaster and the mammalian p21s is in the order of 75-80% mRNA (of 1.2 kb in length) is already present in encysted gastrulae, and the levels increase, reaching a maximum before emergence. On the contrary, both the amount of p21ras and its GTP-binding activity are low prior to emergence and rises afterwards. These results suggest that p21ras expression is regulated post-transcriptionally, and that its function(s) is needed for post-hatching events, the more likely being the resumption of cell proliferation.

Amino Acid Sequence↗
PubMed1988

Isolation of cDNA clones coding for mitochondrial 16S ribosomal RNA from the crustacean Artemia.

cDNA clones coding for Artemia mitochondrial 16S ribosomal RNA (rRNA) have been isolated. The clones cover from nucleotide 650 of the RNA molecule to its 3' end. The comparison of Artemia sequence with both vertebrate and invertebrate mitochondrial 16S rRNA sequences has shown the existence of regions of high similarity between them. A model for the secondary structure of the 3' half of Artemia mitochondrial 16S rRNA is proposed. The size of the rRNA molecule has been estimated at 1.35 kb. Despite the similarity of the Artemia gene to insect rRNA in size, sequence and secondary structure, the G + C content of the Artemia gene (42%) is closer to that of mammals than to the insect genes. The number of mitochondria in Artemia has been estimated at 1500 per diploid genome in the cyst and 4000 in the nauplius. In contrast, the amount of mt 16S rRNA is constant at all stages of Artemia development.

Animals↗
PubMed1987

Identification of the transcriptional initiation site of ribosomal RNA genes in the crustacean Artemia.

The proximal part of the Intergenic Spacer, as well as most of the External Transcribed Spacer of the ribosomal RNA type I genes from the crustacean Artemia have been sequenced. We have identified in the Intergenic Spacer five repeats of around 600 bp in length and, possibly, two imperfect or truncated repeats, derived from the principal ones. These sequences are separated by 485 bp from the 17S rRNA coding sequence. We have also identified the start point of transcription by S1 nuclease analysis. This start point is found 248 bp inside the first repeat. The sequence around the start point shows homology with that described for other members of the same phylum, mostly insects. The most conserved regions are from -1 to +25, and the G residue at position -16. At least the three 600-bp repeats upstream from that containing the promoter also contain the start point sequence, and could therefore act as initiation sites for snPIRNA and/or as enhancer sequences for ribosomal RNA gene transcription.

Animals↗
PubMed1987

Immunological relationships between Artemia RNA polymerases and between RNA polymerases II from different eukaryotic organisms.

Rabbit antibodies against Artemia RNA polymerase II have been raised and utilized to study the immunological relationships between the subunits from RNA polymerases I, II and III from this organism and RNA polymerase II from other eukaryotes. We describe here for the first time the subunit structure of Artemia RNA polymerases I and III. These enzymes have 9 and 13 subunits respectively. The anti-RNA polymerase II antibodies recognize two subunits of 19.4 and 18 kDa common to the three enzymes, and another subunit of 25.6 kDa common to RNA polymerases II and III. The antibodies against Artemia RNA polymerase II also react with the subunits of high molecular weight and with subunits of around 25 and 33 kDa of RNA polymerase II from other eukaryotes (Drosophila melanogaster, Chironomus thummi, triticum (wheat) and Rattus (rat]. This interspecies relatedness is a common feature of eukaryotic RNA polymerases.

Animals↗
PubMed1986

Satellite DNA in the crustacean Artemia.

We have isolated a satellite fraction from the Artemia genome by both restriction endonuclease digestion and equilibrium density centrifugation in CsCl gradients containing ligand dye Hoechst 33258. Satellite DNA was arranged in long stretches (approx. 23 kb) of tandem repeats of a basic unit of 113 bp. The basic unit has been sequenced, showing a G + C content very close to that of total DNA. Different amounts of satellite were present in several populations of Artemia, whereas it was absent from others.

Animals↗
PubMed1986

Characterization of two types of rRNA gene repeat units from the crustacean Artemia.

We have previously described that Artemia rRNA genes are organized with a basic repeat unit of 16.5 kb [Cruces et al., Biochem. Biophys. Res. Commun. 98 (1981) 404-409]. Here we describe the organization of the DNA coding for rRNA of a different population of this crustacean that has a repeat unit of 12.2 kb. Both types of repeat units have been cloned and the organization of the external spacers studied by restriction analysis. Both external spacers contain repeated sequences, but they are not homologous to each other. Sequences from the external spacer of the 16.5 kb repeat are also found elsewhere in the genome, within sequences not related to rRNA genes.

Animals↗
PubMed1984

Purification and subunit structure of RNA polymerase II from different stages of Artemia development.

RNA polymerase II has been purified from different stages of Artemia development: cryptobiotic gastrulae, developing embryos and nauplii. RNA polymerase from dormant and developing embryos consists of 12 subunits of 205 000, 140 000, 32 500, 25 600, 22 000, 19 400, 18 000, 16 800, 147 000, 14 000, 12 700 and 11 500 daltons, as determined by dodecyl sulphate polyacrylamide gel electrophoresis. The enzyme from larvae contains the same polypeptides except for the higher-molecular-mass component: the larval enzyme has a subunit of 172 kDa instead of the 205-kDa subunit present in the enzyme purified from embryos. Incubation of embryonic RNA polymerase II with larval extracts results in the conversion of the 205-kDa subunit into the 172-kDa one. This conversion is inhibited by soybean trypsin inhibitor, a compound which inhibits three proteases induced during Artemia early larval development. RNA polymerase II purified from a mixture of embryos and larvae contain only the 172-kDa subunit. Our results indicate that the 172-kDa subunit present in RNA polymerase II purified from larvae is produced by proteolysis of the 205-kDa subunit during the extraction and purification of the enzyme and therefore that Artemia has only one class of RNA polymerase II.

Animals↗
PubMed1984

Antibodies to vimentin intermediate filaments in sera from patients with systemic lupus erythematosus.

Sera from patients with systemic lupus erythematosus and from healthy subjects were tested, using immunofluorescence and blotting techniques, for the presence of antibodies to intermediate filaments of the cytoskeleton of human skin fibroblasts. Both techniques showed that antibodies to intermediate filaments were found in a higher proportion of sera from patients (53%) than healthy subjects (9%). The antigen target was found to be the protein band that corresponded to vimentin (Mr 57,000).

Adolescent↗
PubMed1984

Western blots.

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Electrophoresis, Polyacrylamide Gel↗
PubMed1982

Purification and characterization of a novel UpN-specific endoribonuclease VI from Artemia larvae.

Artemia larval ribonuclease (Sebastián, J., and Heredia, C. F., (1978) Eur. J. Bichem. 90, 405-411) has been purified near homogeneity and its properties were studied. It consists of a single polypeptide chain of 38,000 daltons. It requires a divalent cation for activity. Ca2+ is the most effective among the metals tested. The metal dependence of the activity is biphasic. Maximal activity is obtained at 5-10 mM. In the absence of metals and chelating agents in the assay, 30-40% of the activity is observed. However, if chelating agents are added, the activity is abolished. At low concentrations of free metal (1-20 microM), 30-40% of maximal activity is obtained with Ca2+ or Mn2+, but not with Mg2+, Ca2+, but not Mn2+ or Mg2+, protects the enzyme from thermal inactivation. The best substrates for Artemia ribonuclease are poly(U) and poly(A), although with the latter it has only 10% the activity shown with the former. Using poly(U) as substrate, the products of a terminal digestion are P-2':3'-Urd and 3'-UMP. Using dinucleoside monophosphates as substrates, the enzyme is highly specific for a U residue at the 3' side of the phosphodiester bond (UpN), especially UpA, being inactive if the U residue is at the 5' side (NpU). Although some of its properties are similar to other eukaryotic or prokaryotic ribonucleases, its high specificity for UpN bonds suggest that this is a new type of ribonuclease. Moreover, it is a potentially useful enzyme for RNA analysis and/or sequencing.

Animals↗
PubMed1980

Specific association of simian virus 40 tumor antigen with simian virus 40 chromatin.

Simian virus 40 tumor antigen (SV40 T antigen) was bound to both replicating and fully replicated SV40 chromatin extracted with a low-salt buffer from the nuclei of infected cells, and at least a part of the association was tight specific. T antigen cosedimented on sucrose gradients with SV40 chromatin, and T antigen-chromatin complexes could be precipitated from the nuclear extract specifically with anti-T serum. From 10 to 20% of viral DNA labeled to steady state with [3H]thymidine for 12 h late in infection or 40 to 50% of replicating viral DNA pulse-labeled for 5 min was associated with T antigen in such immunoprecipitates. After reaction with antibody, most of the T antigen-chromatin complex was stable to washing with 0.5 M NaCl, but only about 20% of the DNA label remained in the precipitate after washing with 0.5 M NaCl-0.4% Sarkosyl. This tightly bound class of T antigen was associated preferentially with a subfraction of pulse-labeled replicating DNA which comigrated with an SV40 form I marker. A tight binding site for T antigen was identified tentatively by removing the histones with dextran sulfate and heparin from immunoprecipitated chromatin labeled with [32P]phosphate to steady state and then digesting the DNA with restriction endonucleases HinfI and HpaII. The site was within the fragment spanning the origin of replication, 0.641 to 0.725 on the SV40 map.

Animals↗
PubMed1979

Transfer of proteins from gels to diazobenzyloxymethyl-paper and detection with antisera: a method for studying antibody specificity and antigen structure.

We describe a rapid and very sensitive method for detecting proteins as antigens after their separation in polyacrylamide/agarose composite gels, with or without sodium dodecyl sulfate. The polyacrylamide matrix is crosslinked with a reagent that can be cleaved with periodate or alkali to facilitate transfer of the protein bands to diazobenzyloxymethyl-paper, where they are coupled covalently. Specific proteins are detected by autoradiography after sequential incubation with unfractionated, unlabeled specific antiserum and 125I-labeled protein A from Staphylococcus aureus. Antibody and protein A can be removed with urea and 2-mercaptoethanol, and the same paper can be probed again with a different antiserum. An antiserum specific for the simian virus 40 virion proteins VP3 and VP2 has been prepared; it does not crossreact with VP1, as demonstrated by this method. An antiserum raised in rabbits against simian virus 40-transformed rabbit kidney cells is shown to be directed primarily against a periodate-sensitive moiety present in tumor (T) antigen from infected or transformed cells, whereas an antiserum raised in rabbits against large T antigen purified from lytically infected monkey kidney cells by electrophoresis in the presence of sodium dodecyl sulfate [Lane, D.P. & Robbins, A.K. (1978) Virology 87, 182-193] is directed primarily against determinants that are not sensitive to periodate.

Antibody Specificity↗